I'm having a problem with my check engine light coming one and off or flashing. on 2008 Chrysler PT Cruiser

My check engine light started to come on. It would go out on its own. Now it also occ flashes. I had the spark plugs and wires replaced and then coil pack replaced. It came on again when the car was idling in driveway for several minutes as well as at a stop light for a period of time. When I accelerate the flashing light promptly goes back out or back to solid. Now it is pretty much staying on again, alternating w short periods of flashing (mostly when sitting at a light, etc). The codes were showing misfires in cylinders. Oddly, now my airbag light is staying on. I am in the process of trading my car in so I don't need the inconvenience of lights on or costly repairs. Obviously, the engine light reflecting a problem will impact the value at trade-in. The local mechanic is at a bit of a loss.